A conventional method has been proposed in which a carbon material, such as carbon black, is blended with a polymer, such as a resin, in order to obtain a composite material with desired conductivity. In recent years, there has been increased demand for composite materials with further improved functionality in order to meet the demand for various devices with higher performance. One method that has been proposed for imparting superior conductivity and mechanical properties on a composite material is a technique that involves blending carbon nanotubes instead of a conventional carbon material.
In one specific example, PTL 1 proposes a method in which carbon nanotubes are blended with a latex with the objective of improving mechanical properties and conductivity of a polymer.
On the other hand, various methods for synthesizing carbon nanotubes have been proposed in recent years (for example, refer to NPL 1) such as a method (hereinafter referred to as the “super growth method”) in which a catalyst activating material such as water is brought into contact with a catalyst in accompaniment to a feedstock gas in the synthesis of carbon nanotubes by CVD in order to dramatically increase the activity and lifetime of the catalyst. Carbon nanotubes with various properties are produced through these methods.